Photoelectric sensor, random accessible active pixel circuit, image sensor and camera

Abstract

Provided is a photoelectric sensor, a random accessible active pixel circuit, an image sensor and a camera. A photoelectric sensor comprises a doped region, a substrate, a doped source region, a doped drain region, and two isolation regions; wherein the doped region is arranged on a bottom surface of the substrate so as to form a photodiode; a cathode of the photodiode is formed in the doped region and is connected to a positive voltage to make the photodiode work in a reverse bias region; wherein the doped source region and the doped drain region are spaced apart on top of the substrate so as to form a field effect transistor; a source is formed on a top surface of the doped source region, and a drain is formed on the top surface of the doped drain region; wherein the two isolation regions are arranged on opposite sides of the substrate, and extend from the doped source region and the doped drain region to the doped region; wherein a gate dielectric layer and a gate between the doped source region and the doped drain region are configured sequentially upwards from the top surface of the substrate; the gate is connected to a voltage to make the field effect transistor select wide dynamic range mode or high gain mode.

What is claimed is: 
     
       1. A photoelectric sensor, comprising:
 a doped region; 
 a substrate; 
 a doped source region; 
 a doped drain region; and 
 two isolation regions, 
 wherein the doped region is arranged on a bottom surface of the substrate to form a photodiode, 
 wherein a cathode of the photodiode is formed in the doped region and is connected to a positive voltage to make the photodiode work in a reverse bias region, 
 wherein the doped source region and the doped drain region are spaced apart on top of the substrate to form a field effect transistor, 
 wherein a source is formed on a top surface of the doped source region, and a drain is formed on the top surface of the doped drain region, 
 wherein the two isolation regions are arranged on opposite sides of the substrate, and extend from the doped source region and the doped drain region to the doped region, to isolate adjacent pixels or adjacent sensors, 
 wherein a gate dielectric layer and a gate between the doped source region and the doped drain region are configured to extend sequentially upwards from the top surface of the substrate, and 
 wherein the gate is connected to a voltage to make the field effect transistor work in a wide dynamic range mode or a high gain mode. 
 
     
     
       2. The photoelectric sensor of  claim 1 , wherein the cathode is formed by an electrode layer plated on the bottom surface of the doped region. 
     
     
       3. The photoelectric sensor of  claim 2 , wherein the electrode layer is a transparent electrode layer. 
     
     
       4. The photoelectric sensor of  claim 1 , wherein, when the substrate is a P-type substrate, the doped region, the doped source region and the doped drain region are all N-type heavily doped regions; and, when the substrate is a N-type substrate, the doped region, the doped source region and the doped drain region are all P-type heavily doped regions. 
     
     
       5. The photoelectric sensor of  claim 1 , wherein the substrate is one of a lightly doped silicon wafer substrate or a silicon epitaxial layer substrate. 
     
     
       6. A random accessible active pixel circuit, comprising:
 a selection transistor; and 
 a photoelectric sensor, 
 wherein the photoelectric sensor comprises a doped region, a substrate, a doped source region, a doped drain region, and two isolation regions, 
 wherein the doped region is arranged on a bottom surface of the substrate to form a photodiode, 
 wherein a cathode of the photodiode is formed in the doped region and is connected to a positive voltage to make the photodiode work in a reverse bias region, 
 wherein the doped source region and the doped drain region are spaced apart on top of the substrate to form a field-effect transistor, 
 wherein a source is formed on a top surface of the doped source region, and a drain is formed on the top surface of the doped drain region, 
 wherein the two isolation regions are arranged on opposite sides of the substrate, and extend from the doped source region and the doped drain region to the doped region, to isolate adjacent pixels or adjacent sensors, 
 wherein a gate dielectric layer and a gate between the doped source region and the doped drain region are configured to extend sequentially upwards from the top surface of the substrate, 
 wherein the gate is connected to a voltage to make the field-effect transistor work in a wide dynamic range mode or a high gain mode, and 
 wherein the drain of the selection transistor is electrically connected to the source of the photoelectric sensor, the source of the selection transistor serves as an output of the random accessible active pixel circuit, and the gate of the selection transistor is used to connect with a positive voltage to turn-on the random accessible active pixel circuit or connect with a negative voltage to turn-off the random accessible active pixel circuit; in the photoelectric sensor, the cathode and the drain are connected in series. 
 
     
     
       7. The random accessible active pixel circuit of  claim 6 , wherein the cathode is formed by an electrode layer plated on the bottom surface of the doped region. 
     
     
       8. The random accessible active pixel circuit of  claim 7 , wherein the electrode layer is a transparent electrode layer. 
     
     
       9. The random accessible active pixel circuit of  claim 6 , wherein, when the substrate is a P-type substrate, the doped region, the doped source region and the doped drain region are all N-type heavily doped regions, and, when the substrate is an N-type substrate, the doped region, the doped source region and the doped drain region are all P-type heavily doped regions. 
     
     
       10. The random accessible active pixel circuit of  claim 6 , wherein the substrate is one of a lightly doped silicon wafer substrate or a silicon epitaxial layer substrate. 
     
     
       11. The random accessible active pixel circuit of  claim 6 , wherein when an operating mode of the random accessible active pixel circuit comprises a wide dynamic range mode, a driving process to make the random accessible active pixel circuit in a wide dynamic range mode comprises:
 applying a voltage to the cathode of the photoelectric sensor to make the photodiode work in a reverse saturation region; and 
 adjusting the voltage applied to the gate of the photoelectric sensor to make the field effect transistor work in an off-state region, and 
 wherein, when the light irradiates a back-side of the substrate of the photoelectric sensor, a photocurrent is generated in the photodiode, and an output current of the random accessible active pixel circuit is linearly related with the light intensity, the operating mode of the random accessible active pixel circuit is a wide dynamic range mode. 
 
     
     
       12. The random accessible active pixel circuit of  claim 6 , wherein when the operating mode of the random accessible active pixel circuit further comprises a high gain mode, a driving process to make the random accessible active pixel circuit in a high gain mode comprises:
 applying a voltage to the cathode of the photoelectric sensor to make the photodiode work in a reverse saturation region; and 
 adjusting the voltage applied to the gate of the photoelectric sensor to make the field effect transistor work in a sub-threshold region, and 
 wherein, when the light irradiates a back-side of the substrate of the photoelectric sensor, a photocurrent is generated in the photodiode, and an output current of the random accessible active pixel circuit is substantially linearly related with the light intensity, the operating mode of the random accessible active pixel circuit is a high gain mode. 
 
     
     
       13. An image sensor comprising:
 a random accessible active pixel circuit, 
 wherein the random accessible active pixel circuit comprises a selection transistor and a photoelectric senor, 
 wherein the photoelectric sensor comprises a doped region, a substrate, a doped source region, a doped drain region, and two isolation regions; 
 wherein the doped region is arranged on a bottom surface of the substrate to form a photodiode, 
 wherein a cathode of the photodiode is formed in the doped region and is connected to a positive voltage to make the photodiode work in a reverse bias region, 
 wherein the doped source region and the doped drain region are spaced apart on top of the substrate to form a field effect transistor, 
 wherein a source is formed on a top surface of the doped source region, and a drain is formed on the top surface of the doped drain region, 
 wherein the two isolation regions are arranged on opposite sides of the substrate, and extend from the doped source region and the doped drain region to the doped region, to isolate adjacent pixels or adjacent sensors, 
 wherein a gate dielectric layer and a gate between the doped source region and the doped drain region are configured to extend sequentially upwards from the top surface of the substrate, 
 wherein the gate is connected to a voltage to make the field effect transistor work in a wide dynamic range mode or a high gain mode, and 
 wherein the drain of the selection transistor is electrically connected to the source of the photoelectric sensor, the source of the selection transistor serves as an output of the random accessible active pixel circuit, and the gate of the selection transistor is used to connect with a positive voltage to turn-on the random accessible active pixel circuit or connect with a negative voltage to turn-off the random accessible active pixel circuit; in the photoelectric sensor, the cathode and the drain are connected in series. 
 
     
     
       14. The image sensor of  claim 13 , wherein an operating mode of the circuit comprises a wide dynamic range mode, a driving process to make the random accessible active pixel circuit in a wide dynamic range mode comprises:
 applying a voltage to the cathode of the photoelectric sensor to make the photodiode work in a reverse saturation region; and 
 adjusting the voltage applied to the gate of the photoelectric sensor to make the field-effect transistor work in an off-state region, and 
 wherein, when light irradiates a back-side of the substrate of the photoelectric sensor, a photocurrent is generated in the photodiode, and an output current of the random accessible active pixel circuit is linearly related with intensity of the light. 
 
     
     
       15. The image sensor of  claim 13 , wherein the operating mode of the random accessible active pixel circuit comprises a high gain mode, a driving process to make the random accessible active pixel circuit in a high gain mode comprising:
 applying a voltage to the cathode of the photoelectric sensor to make the photodiode work in a reverse saturation region; and 
 adjusting the voltage applied to the gate of the photoelectric sensor to make the field-effect transistor work in a sub-threshold region, and 
 wherein, when light irradiates a back-side of the substrate of the photoelectric sensor, a photocurrent is generated in the photodiode, and an output current of the random accessible active pixel circuit is substantially linearly related with intensity of the light. 
 
     
     
       16. A camera comprising the image sensor of  claim 13 .